This invention is directed to a touch sensitive input for electronic wristwatches, electronic calculators, and combinations thereof, and in particular to the use of touch sensitive inputs for use in electronic utilization devices, and in particular to touch sensitive inputs particularly suited for replacing mechanical switches in electronic digital display wristwatches, electronic calculators and miniaturized combination electronic calculators and watches.
Heretofore, the most common input device utilized in small-sized electronic instruments such as electronic calculators, electronic wristwatches and the like have been manually-actuated mechanical switches of the push-button and push-pull variety. Usually, the manually operated switches are the only moveable parts that remain when the instrument is converted over from mechanical operation to electronic operation.
For example, balance wheel mechanical wristwatches included a mechanical movement having a considerable number of miniaturized wheels, axles, springs, screws and the like. By comparison, electronic wristwatches utilize a quartz crystal vibrator as a time standard, with the remaining elements being integrated circuit chips, and an occasional resistor and/or capacitor. Thus, in LED and LCD digital display electronic wristwatches, the only mechanical parts therein are the input switches, which input switches are required in LED wristwatches for turning on the display elements and for correcting the time displayed thereby, and which input switches are needed in LCD wristwatches for correcting the time displayed thereby and if desired, selectively illuminating the LCD displays. Nevertheless, these mechanical switches have proved to be less than completely satisfactory since same render more difficult the waterproofing of the interior of the electronic wristwatch and additionally, decrease the reliability of the input operations to be effected thereby.
Similarly, in small-sized electronic table calculators and calculators included in electronic wristwatches, the inputs are effected by a keyboard, with each key being a mechanical reed switch or contact spring switch. Since such calculators require a considerable number of input keys for inputting each of the numbers, registration, function, decimal point, equal and clear, a large number of keys must be disposed in a small area, resulting in frequent displacement of keys other than the key desired. Although integrated circuitry has permitted each of the electronic components of the calculator to be miniaturized, a similar miniaturization in the scale of the input keys renders it impossible for the input keys to be manually actuated by a finger, without actuating a plurality of surrounding keys. To overcome this problem, electronic wristwatches having calculators therein have been provided with an actuating member for pushing the keys in order to actuate same thereby preventing inadvertent actuation of the input keys surrounding the input key that the operator desires to actuate. Accordingly, a touch sensitive input for small-sized electronic utilization devices such as electronic calculators and electronic wristwatches that improves reliability and prevents selecting unwanted input functions when a plurality of compact input switches are required is desired.